Coordinating market-based climate instruments is a central challenge for climate policy, yet the institutional mechanisms through which centralized governance systems pursue such integration remain insufficiently understood. This study examines how China coordinates Green Electricity Certificates (GEC) and Carbon Emissions Trading (CET), two instruments administered by separate bureaucracies. Drawing on 1,137 policy documents from 2017 to 2024 across 29 provinces, we combine BERTopic, cosine similarity analysis, and Bayesian Exponential Random Graph Models to trace central discourse convergence, provincial transmission heterogeneity, and horizontal coordination dynamics. Three findings emerge. First, central policy discourse shows rapid GEC-CET convergence after the 2020 carbon-neutrality pledge, with cross-referenced policy objectives rising from 7.3% to 18.6% within 24 months. This compressed trajectory contrasts with the more incremental development of the EU ETS, while also leaving important technical protocols, including double-counting safeguards, insufficiently specified. Second, provincial transmission exhibits persistent core-periphery gradients within the observation period: eastern provinces show high alignment with central policy discourse, whereas several western and resource-dependent provinces remain lower despite positive growth. Third, network reciprocity and transitive closure are positively associated with the formation of policy-integration ties alongside hierarchical policy-node effects and policy-tool covariates. Instrument associations are context-dependent: economic incentives are more strongly associated with integration in mature market settings, while capacity-building tools are more salient in regions with emerging institutional infrastructure. These findings contribute to climate policy integration research by showing how compressed institutional timelines, uneven local capacity, and horizontal network dynamics jointly shape coordination between market-based climate instruments, while highlighting implications for carbon-accounting readiness under the EU Carbon Border Adjustment Mechanism and regionally differentiated transition planning.
